During a horde spawning at the first Grimoire of the map I noticed rats dying by themselves soon after spawning:
The tree passage is flanked by two tall trees where rats climb down and jump the last few meters. It looks like as soon as the climbing animation ends and they start dropping they instantly die. I observed this during the start and end of the horde on both trees flanking the passage.
Unfortunately I wasn’t recording. Can anyone else confirm this?